1. Field of the Invention
The present invention concerns the coordination of communications systems and more particularly, the coordination of mobile units in a sleep mode.
2. Description of the Related Art
Under the 802.16e standard, mobile units that are communicating with a base station may enter a sleep mode. In the sleep mode, certain portions of the mobile unit may be temporarily shut down in an effort to conserve battery life. During this sleep mode, the mobile unit maintains its registration with the base station, and as such, set-up times for certain applications, like VoIP or push-to-talk calls, remains quick.
In sleep mode, each mobile unit sets its wake-up times and communicates this with the base station. In response, the base station will transmit a traffic indicator to the mobile units during each mobile unit's wake-up time. As such, the wake-up times in sleep mode are uncoordinated and the base station must constantly transmit traffic indicators to the mobile units during their wake-up times. Even worse, the base station must transmit the traffic indicator during each wake-up time for each mobile unit, even if the traffic indicator indicates that there is currently no traffic for the mobile units. This process places a considerable strain on the base station and may tie up network resources.